Write

What are ... ?

Periodicals include newspapers, popular/general magazines, and scholarly journals. Each of these is published on a regular or periodic (daily, weekly, monthly) basis, hence the name--periodicals.

Journals

Journals are the primary means of communication among scholars within a particular field. Scholarly or academic journals usually present original research, and sometimes (but not always) will be peer-reviewed or refereed. Professional or trade journals provide information to those in the field or industry.

Magazines

General/popular magazines are usually commercially published; they cover current or popular topics, and may be purchased at newstands/grocery stores. Magazines provide good overviews of a topic.